There are a number of labeling systems adapted to apply pressure-sensitive labels to articles or containers at a label-applying station. A typical prior art system is illustrated schematically in FIG. 1. Labels (1) are carried initially by a web (2) with the adhesive side of the label facing toward the web, and the adhesive holding the label to the web. The labels are delivered to a vacuum drum (7) following stripping from the web (2) at a label pick-up station (5), and deposited on the vacuum drum (7). The vacuum drum (7) continuously advances the stripped labels in a given direction to meet articles to be labeled (3) at a label-applying station (4). Simultaneously, articles to be labeled (3) are continuously advanced past the label applying station (4).
The speed of advance of the articles to be labeled 3 and the speed of advance of the web (2) are sensed continuously by electronic means, and the speed of advance of the web (2) is adjusted as necessary to match the speed of advance of the articles to be labeled (3). In FIG. 1, the articles to be labeled (3) are rotating as they contact the adhesive surface of the label at label applying site (4), thereby fixing the label to the article to be labeled (3). Some of the prior art devices utilize a pressure-sensitive labeler with an intermediately moving web. More recent devices utilize a continuously moving web pressure-sensitive labeler. Typical examples of these various devices will be found in U.S. Pat. Nos. 4,842,660; 4,687,535; and 5,256,239.
The aforementioned patents, while describing effective labeling systems and equipment, are not perfect and, on occasion, “incorrect” or faulty labels may be applied to containers. Incorrect/faulty labels are wrong labels or labels with poor or illegible lot numbers or expiration dates and/or incorrect bar code or part numbers. This is a matter of particular concern to packagers of pharmaceuticals. An incorrectly labeled pharmaceutical container could lead to a costly product recall, and might result in serious injury or even death. The end user relies on the label to take medicine according to a doctor's instructions and could, in fact, be taking the wrong medicine or following wrong directions with adverse results. Accordingly, equipment and systems have been developed for detecting the presence of incorrect/faulty labels. This detection may occur both prior to labeling and subsequent to labeling, or both: U.S. Pat. Nos. 2,551,364 and 4,662,971 are examples of labeling equipment that provide error detection prior to application of the labels.
U.S. Pat. No. 5,405,482 describes an advance over the aforementioned patents in that the scanning and removal of incorrect/faulty labels can be conducted without interrupting the essentially continuous operation of the labeling equipment. The label scanner (8) is positioned to “read” the labels while they are still positioned on the carrier web, just prior to the label pick-up station (5) and vacuum roll (7) which will remove the label from the web. A “bad” label-removal unit is positioned between the vacuum roll label pick-up point (5) and the point (4) at which the vacuum roll normally releases and applies a label to a container (3) and is controlled by information from the scanning unit (8) such that when an incorrect label is identified by the scanner, the information is transmitted to and actuates a label-removing device. It is only necessary that the rate and time of label travel be coordinated so that the label removed is the detected incorrect label and not one of the proper labels. There are some serious drawbacks to the detection system of U.S. Pat. No. 5,405,482. As noted in the patent, the adhesive strength of the label coating overcomes the vacuum strength of the vacuum drum such that the incorrect label is wrapped around the removal roller of the label removal device. These removed labels accumulate on the removal roller and eventually must be removed from the roller by a machine operator. In this regard, see U.S. Pat. No. 5,405,482, column 3, lines 51-54, and column 4, lines 12-14. Because these labels are strongly adhered to each other, they are not readily separated from each other for individual reconciliation and one must depend on the weight of the accumulated, adhered block of labels relative to the weight of a single label for reconciliation purposes, a procedure that is inherently inaccurate and/or inefficient.
The deficiency in the system of U.S. Pat. No. 5,405,482 and all the previously discussed patents is the absence of means for detecting, isolating, and reconciling incorrect/faulty labels prior to label application. In dealing with something as sensitive as pharmaceuticals, one must consider the serious dangers inherent in the fact that any mechanical system may go out of adjustment. Under such circumstances, it is possible that the label removed is not the label that the scanner detected as incorrect, with the result that a correct label is removed and the incorrect/faulty label continues on into the system. In U.S. Pat. No. 5,405,482, at column 4, lines 18-19, it is noted that “unlabeled bottles are easily thereafter identified by operating personnel and may even be reused.” While such detection procedures make identification of the skipped unlabeled container relatively easy, they do not provide an easy and efficient reconciliation between incorrect/faulty labels identified and incorrect/faulty labels removed. It is difficult to impossible for the operator to peel off individual labels from the adhered block of accumulated label faults on the label-remover roll and examine them individually for faults or for reconciliation. Further, by the time the roller has been cleared of the accumulated, adhered “incorrect” or faulty labels, and a reconciliation attempted, a container with an incorrect/faulty label, which through error in the detection process, may be far down the line, and mixed in with the large number of labeled containers coming off the labeling line.